Outline

Objective: Measurement of tissue oxygenation (ptiO2) parallel to ICP was possible until now with a separate sensor (Licox, Neurotrend) only. This led to development of multilumen introducers to avoid several burr holes. However, different monitors, cables and technologies had to be combined. We present the first clinical results of a new catheter which combines an oxygen sensitive sensor along with an ICP- and temperature probe (Raumedic PTO) together with the experiences of the oxygen data logger (Raumedic MPRlogO).

Methods: In vitro testing with 18 PTO sensors was performed in 7, 14 and 57mmHg oxygen tension calibrated tonometer solutions. Different types of oxygen probe technologies were tested in animal experiments (pigs). Clinical investigation was done with 11 PTO probes in patients suffering subarachnoid hemorrhage or severe head injury. The PTO sensor was placed frontal along with a Licox ptiO2 sensor (Integra). Additional, ICP was measured by a ventricular catheter in three patients. All data from the PTO-probe were recorded using the MPRlogO and using a PC for the Licox probe.

Results: Deviation of pO2 was 0,3-1,4mmHg in all three oxygen concentrations. The 90%-reactivity time was faster compared to the Licox sensor. In animal studies, performance of the PTO probe was compared to Licox. These experiments made clear, that the size of the oxygen sensitive area as well as the material in which the sensor was embedded was extremely important for sensor performance. For Licox readings ≥10mmHg, mean deviation was <5mmHg (except 5%). Low oxygen reading was seen in both probes if catheters were placed correctly, but differed in one patient with a small blood clot around the catheters. In all patients, ICP measured by the PTO probe was comparable to the ventricular probes.

Conclusions: In our first results, the new combined PTO probe in combination with the MPRlogO was a robust monitoring tool for multiparametric measurements in neurosurgical patients. ptiO2 measurements are comparable to Licox, and due to a larger oxygen sensitive area of 22mm2 compard to Licox (14mm2) together with a photooptic O2 detection, the new sensor seems to become a significant place in neurosurgical practice.